Device for conducting images



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DEVICE FOR CONDUCTING IMAGES Filed March 1l. 1954 3 Sheets-Sheet 2 5, m5ILL- March 10, 1959 E. E. sHr-:LDON 2,877,368

DEVICE FOR CONDUCTING IMAGES Filed March 1l, 1954 3 Sheets-Sheet 3 'lfffUnited States Patent O DEVICE FOR CONDUCTING IMAGES Edward EmanuelSheldon, New York, N. Y.

Application March 11, 1954, Serial No. 415,669

Claims. (Cl. 313-65) This invention relates to a novel instrument forexamination of the interior of the parts, channels or passages which areinaccessible to the examiner and has the common subject matter with myU. S. Patent No. 2,764,- 149, issued in September 25, 1956, which wasco-pending and had a common subject matter with my application Ser. No.15,222, filed on March 16, 1948, and now abandoned. Due to the inabilityof light to bend around the corners, the present instruments used forsuch examinations have to be straight and rigid so that the eye of theexaminer and the examined part are in one straight line. The instrumentsusing optical lenses or prisms will not help in the situation when theshape and the size of the examined part is variable and unknown in advance. In such a case, the position of the curves and angulations in theexamined parts or passages is unknown and therefore the lenses or prismscannot be positioned to anticipate deviations of the axis ot theexamined channel from the straight line.

The purpose of this invention is to provide means for inspection ofinaccessible channels, such as hollow parts of machinery or of otherinaccessible tortuous passages. My vdevice may be introduced inside of apart which cannot be inspected visually without dismantling ordestroying the whole machine and will transmit the image of said part tothe observer outside of said part. My invention will be especiallyuseful for the examination of coils and pipesor other curved structures.My device can be also used as a probe to be inserted into a solid objectand to transmit information about its internal structure.

Another objective of my invention is to intensify the image of theexamined internal parts or passages so that the final image will bepresented to the observer with the luminosity facilitating inspection ofsaid image.

Another purpose of my invention is to enable simultaneous observation ofsaid inaccessible parts by many examiners, situated in close or remotelocations, which was not possible until now.

Another objective of this invention is to change, decrease or amplifythe contrast of the image of the examined part.

The objectives of my invention are realized by a novel device which isflexible to allow its introduction into the examined part regardless ofits curvatures or angulations and which after its introduction into theexamined part will produce a light image of said part, will nextfconvert said light image into video signals and will transmit saidvideo signals outside of said part. Video signals are reconverted inreceivers outside of the examined part into visible images forinspection or recording. My intrascopic device can produce black andwhite images, as well as multi-color images, showing faithfully orarbitrarily lthe colors of the examined part.

In particular this novel device makes use of a television pick-up tubeconsisting of two separate independent elements which can be introducedseparately into the examined part and which after introduction work inPatented Mar. 1o, 1959 cooperation as a television camera. As each ofthese two separate elements is smaller in size than any conventionaltelevision camera can be made, this novel television camera can beintroduced into locations which, because of small size or tortuous shapeof passages leading to them, were inaccessible to the most miniaturizedtelevision cameras known in the art.

Another marked improvement in my novel television camera is eliminationof magnetic deecting coils which are bulky and occupy so much space thateven a small television tube using them cannot be introduced into narrowpassages. The use of conventional electrostatic deecting system resultsinto a marked distortion of images especially in pick-up tubes using theslow scanning electron beam. These drawbacks are eliminated in my intrascope and therefore in spite of its very small size it is capable ofproducing images of a good definition and contrast.

In some applications even this novel intrascope utilizing a pick-up tubedivided into two separate independent elements cannot be introduced intovery narrow or tortuous passages. ln such cases I use a novel imageconductor in combination with my television pick-up tube. The novelimage conductor consists of a flexible guide of material having a highindex of refraction and critical angle of rellection which prevents theescape of the light from said guide. The novel image conductor may bemade of any desired size or shape and therefore it can penetrate themost inaccessible locations and can transmit the image therefrom to thetelevision pick-up tube or directly to the outside to the observer.

In the drawings:

Fig. 1 represents a partially sectioned view of the novel intrascope;

Figs. la, 1b and lc show a modification of the intrascope;

Fig. 1d shows an intrascope with a simplified television camera tube;

Fig. 2 shows a combination of light image conductor with a televisionpick-up tube;

Fig. 2a and 2b represent a modification of the combination comprising animage conductor and a pick-up tube;

Fig. 3 represents a modied embodiment of my intrascope provided withimage conductor;

Fig. 3a represents a modication of my intrascope in which imageconductor is in contact with the distal end of the intrascope;

Figs. 4 and 5 represent a simplified intrascope provided with a lightimage conductor; and

Fig. 6 represents an embodiment of my intrascope provided with an imageamplifying tube.

The new device which may be called the intrascope 1 is shown in Fig. l.The handle 2 is a hollow tube of diameter corresponding to the examinedpart. The handle may be rigid or semi-flexible or completely flexibleaccording to the part to be examined. At the end of the handle beginsthe flexible part 2a of the intrascope which also has width and lengthsuitable for the size of the examined part. In case the intrascope isused for examination of fragile parts, the part 2a must be very iiexibleand pliable in order to avoid damage to the wall of the examined part.The basic feature of the material for the tiexible part of theintrascope is therefore that it must be easily bent and molded by thewalls of the passages in which it is being introduced. Such material maybe a suitable plastic, or rubber 26 of the type used by Davol RubberCompany of Providence, Rhode Island, for their gastric tubes. In casethe intrascope is used for investigation of sturdy parts or of machinerythe part 2a may be obviously more rigid. The liexible part 2a of theintrascope may be in such a case made of the stainless steel spiralsheet designed not only for durability but also to maintain the properdegree of flexibility and elasticity. The metal spiral is tapered toinsure its uniform bending. The intrascope may be covered with an outertubing 26a such as of neoprene. This prevents dust particles andmoisture from alecting the optical and pick-up system located inside ofthe intrascope. At thc end of the liexible part there is a semi-liexibletip 3 which may be screwed on the iiexible part and can be easilyremoved giving thereby access to the inner structures of the intrascope.The tip consists of a rubber conical finger and serves to facilitate thegliding of the intrascope within the examined part. In order tofacilitate the introduction of the intrascope `into parts which have nocurves my device can be made semi-rigid by inserting into it asemi-rigid stilet. In case the intrascope is used as a probe forinsertion into a solid object the tip 3 should be preferably rigid andsharply pointed to be able to pierce the examined object.

In some cases the examined part has to be distended by air or fluidinsuliiation prior to the examination. A special air pump attachment 44and a channel 44a in the intrascope is provided for this purpose. Thechannel 44a also may serve to evacuate contents of the examined partbefore examination to improve visibility. The knob 45 on the proximalend of the intrascope serves to indicate to the examiner the position ofwindows 12 and 18 of the intrascope. In some cases the layer 26 shouldbe of a dielectric material to prevent any short-circuits.

In the distal end of the tlexible part of the intrascope there is ahousing box 5 containing the illumination system 7. The box 5 may alsobe attached to the inner walls of the intrascope by means of thebrackets or may be held by springs. It is obvious that there are manymeans for attachment of the box 5 which are well known in the art. Allwalls of the housing box 5 except the one facing the television pick-uptube 16 are provided with windows for transmission of the light from theilluminating system 7. These windows are correlated with the windows 12in the flexible part of the intrascope which transmit the light from theilluminating system to the examined part. In some cases the windows 12may be made to extend over the circumference of the intrascope. In somecases the window to transmit illumination from the light source to theexamined part may also be provided in the distal end of the intrascopeinstead of being in its side walls, and in such case the tip may be madeof transparent material or may be omitted. Windows 12 may be providedwith shutters which can be controlled from the proximal end of theintrascope which is outside of the examined part.

The illuminating system may consist of the electrical bulb 7. Theelectrical bulb may be mounted in the housing box 5 by means of a socket7a. In some cases it is advantageous to use the objective lens 11between the light bulb and window 12 in order to concentrate the lighton one iield. The lens may be held in position by brackets 11a. Thelight bulb is activated by the source of electrical power 9 situatedoutside of the examined part. Such a source may be the commercialelectrical current or battery of dry cells. The exible electrical cable8 leads from the socket 7a to said outside source of electrical current9. The cable is a lacquered, double insulated electric wire, is coveredin addition with liquid rubber and is vulcanized in order to prevent ashort circuit. The housing unit 5 may be in some cases omitted and thelight source may be attached to the socket 7a which is held by brackets.

In the exible part 2a proximally to the housing box 5, there is a rigidnon-transparent housing compartment 14 containing the optical system15and the novel television pick-up tube 16a and 16b. The housing 14 hasan opening 17 in which the optical system 15 is lodged and which servesto admit the image of the examined part. This opening is correlated withwindows 18 in the flexible part of the intrascope which transmit theimage of the examined part. In some cases the windows 18 may be made toextend over all the circumference of the intrascope. The windows 18 maybe provided with shutters operated from the proximal end of theintrascope which is externally to the examined part. The housing ll4containing the television pick-up tube 16a and 16b and the opticalsystem may be attached to the inner wall of the exible part 2a of theintrascope by means of brackets or may be held by springs 27a. As thehousing box its into the encasing holding member 26 and is held by ittightly, in some cases no additional supporting means such as springsare necessary.

The optical system 15 may consist of 90 gable prism 20 and of lens 21.The optical system may have its own housing unit instead of being lodgedin the compartment 14 and may be then introduced into the intrascopeseparately.

In some cases it is desirable to have a large iield of vision and at thesame time to preserve the necessary magnification of the examined part.In case the magnification of the examined part is not necessary a largeiield of vision can be obtained by using the lens providing field ofvision instead of the usual 45-50". The image produced by the opticalsystem is inverted but it can be reverted to the original positioneither by an additional lens or electron-optically in the viewing tube.The rotating mirror may also serve to admit image either through window18 or 18a without rotating the whole camera 16.

The housing box 14 contains the novel miniature television camera 16which was designed to reduce to the minimum the size of the televisioncamera. The television pick-up tubes known previously in the art couldbe miniaturized only to a certain degree, which was not suicient incertain applications as some of the examined parts are too small toallow the introduction even of the smallest conventional pick-up tube.This is true especially for the type of tubes having external deflectingcoils such as of magnetic or electro-magnetic type, and in suchsituations, my novel camera 16 will be very suitable as it does notrequire any external deflecting or focusing coils at all. The camera 16consists of two vacuum tubes 16a and 16b. The tube 16a has an electrongun 28 which produces an electron beam 29. The electron beam 29 isfocused by electrostatic lield 30. The electronoptical system forfocusing the electron beam 29 may be simplified and markedly reduced inlength by using the unipotential electrostatic lens instead of the usualtwo-lens system. The electron beam 29 is deflected by electrostaticplates 30a and 30b in two perpendicular to each other planes. Theelectrostatic plates are energized by signals from saw-tooth generators32 which are situated outside of the examined part. The generators 32are connected with electrostatic plates 30a and 30b by means of exiblewires. One deflecting eld is produced by the horizontal deection plates30a and may have line frequency such as 515,000 cycles per second.Another deliecting field is provided by the vertical deection plates 30band may have field frequency such as 15-60 cycles per second. In thisway the electron beam 29 is made to scan the fluorescent screen 31 in aregular television raster. The deliection system may be furthersimplified and miniaturized by having only horizontal deflection plates30a. The vertical deections 30b are eliminated and the verticaldetlection of the fluorescent light spot is provided by the rotatingdrum 71 with plural mirrors 72 as shown in Fig. 1d. The liuorescentscreen 31 may be provided with electron transparent metallic conductingbacking layer 31a such as of aluminum. The fluorescent screen 31 must beof a phosphor of a very short persistence in order to obtain a goodresolution of the image. ZnO has decay time of 1 microsecond and issuitable for this purpose. Still better results may be obtained by meansof ZnS phosphor and using only ultra-violet cornponent of its uorescentemission which has decay time of M microsecond. In some cases, it ispreferable to mak'e the fluorescent screen 31 of semi-spherical curvedshape as it will improve definition of the ying light spot. Thefluorescent layer 31 may also be deposited on the supporting mesh screeninstead of being deposited on the wall of the vacuum tube. This willimprove definition of the flying light spot.

The vacuum tube 16a operates in combination with the vacuum tube 16bforming together the novel television camera 16. The vacuum tube 16h hasa photoemissive electrode 33 which may be deposited or attached to oneof the walls of said vacuum tube. In some cases it is preferable toprovide a light transparent conducting layer 33b such as of materialknown in the trade as Nesa, or of compounds of tin or cadmium, on theside of said photoemissive electrode 33 facing the uorescent screen 31.The photoemissive electrode 33 may be of CsOAg of caesium, lithium orrubidium on antimony, arsenic or bismuth. At the opposite end of thevacuum tube 16b there is provided photocathode 34 which consists of alight transparent signal plate 34a, a light transparent insulating layer34h and of a photoemissive mosaic 34e. The signal plate 34a may be athin transparent layer of metal or other conducting material. Theinsulating layer 34b may be of mica, silica, or other transparentdielectric material and photoemissive mosaic 34e may be of CsOAg or ofcaesiurn, rubidium or lithium on antimony, arsenic or bismuth. In somecases the photoemissive layer 34C may be, instead of a mosaic, also ofcontinuous type. In cases in which electrostatic focusing field 23 isused to focus the scanning electron beam 33a on the mosaic 34e, muchbetter resolution will be obtained by making such mosaic of a curvedsemispherical shape. ln addition, the use of such spherically shapedphotocathode will eliminate instability of the image which is verymarked when using electrostatic fields for focusing a slow electronbeam.

The light image of the examined part isprojected by the optical systemon the photocathode 34 of the vacnum tube 16b. The light image producesemission of photoelectrons from the layer 34e. As a result a positivecharge image having the pattern of said light image is left on thephotoemissive mosaic 34C. Both vacuum tubes 16a and 16b are held inapposition to each other and in such a manner that the fluorescentscreen 31 of the vacuum tube 16a is adjacent to the photoemissiveelectrode 33 of the tube 16b. The scanning electron beam 29 impinging onthe fluorescent screen 31 produces a light spot at each point of itsimpingement. The scanning illumination excites the photoemissiveelectrode 33 and produces thereby a fine scanning beam of photoelectrons33a. The photoelectron beam 33a is ot the scanning type because it isproduced by the scanning electron beam 29. The photoelectron beam 33amay be further focused by electrostatic fields 23. In some cases thephotoemissive electrode 33 and the mosaic 34 are disposed so close toeach other that the focusing fields may be eliminated which will furtherreduce the size of the vacuum tube 16h. When the focusing elds areomitted I found that separation of electrode 33 and mosaic 34 should notexceed 0.25 millimeter.

In a vacuum tube 16b instead of the photoemissive mosaic I may also usea photoconductive photocathode such as shown below in Fig. 2b. Thephotoconductive photocathode comprises a conducting signal plate 34awhich is connected to the circuit producing video signals and aphotoconductive layer 34e deposited thereon as shown in Fig. 2b. Thephotoconductive layer may be of selenium, zinc selenide or of antimonysulde or of other photoconducting materials.

Another important modification of the vacuum tube 16b was accomplishedby eliminating the photoemissive electrode 33. In this embodiment ofinvention as shown in tube 75 in Fig. 1c, the uoresccnt light scansdirectly '6 the photoemissive mosaic 34e. The emission of photoelectronsfrom the photoemissive mosaic 34e produces signals in the capacitativelycoupled signal plate 34a. These signals are converted into video signalsin the manner well known in the art.

In examination of stationary objects my intrascope may be furthersimplified by using as a source of scanning light instead of a vacuumtube 16a, a steady source of light such as an electrical bulb 74 incombination with an oscillating mirror 73 or rotating drum as shown inFig. 1c. The oscillating mirror or drum is limited in frequency ofoscillations; therefore video signals produced [Dy this device must bestored until the whole image is assembled. It is also possible to useinstead of a storage tube for video signals, a receiver tube such as akinescope having a memory screen such as dark trace screen. Also afacsimile receiver can be used for this purpose. The pick-up tube 75 maybe also simplified by eliminating the electrode 33 as was explainedabove. The oscillating mirror may be mounted on a pivot and lmay beenergized by solenoids through which the current lof high frequency isowing. One set of coils serve to move the mirror in horizontal axis.Another set of coils is vibrating the mirror on vertical axis. Theaction of both coils makes the mirror oscillate in such a manner thatthe light reflected by said mirror will scan the area on which it isprojected in the same manner as the flying spot which is produced by acathode-ray tube. The construction of an oscillating mirror is wellknown in the art and it is believed therefore that its further detaileddescription will only serve to complicate the drawings.

The electron beam 33a may be of high vel-ocity such as used in theiconoscope type of television pick-up tubes or may be of a slowvelocity. In this embodiment of my invention, I use the slow scanningelectron beam. It is to be understood however that the fast scanningelec- ,tron beam may be used in my invention as well. The ielectron beam33a scanning across the charge image stored in the mosaic 34C convertssaid image into electrical signals which appear at the signal plate 34a.These electrical signals can be converted into video signals over theresistance in the manner well known in the art. The video signals aretransmitted by the flexible coaxial cable 43 from the ntrascope withinthe examined part to the video amplifiers 43a outside of said part. Theamplified signals are transmitted from the amplifiers to the viewingtube of kinescope type 37 and are reconstructed therein into the visibleimage representing the image of the examined part. The viewing tube maybe of kinescope type and does not have to be described in detail as itis well known in the art. The examined part will appear on thefluorescent screen 37a of the viewing tube where it can be inspected bymany examiners. Transmission of the image from the amplifier 43a to theviewing tube pan be done by coaxial cable 43 or by high frequency waves.The image can be sent therefore not only to the immediate, but also tothe remote receivers or may be transmitted to multiple independentviewing tubes for the benefit of many examiners which was one of theobjectives of this invention. The image on the viewing tube 37 may alsobe photographed simultaneously with the intrascopic examination in orderto make a permanent record which was another purpose of this invention.

The contrast of the reproduced image may be changed, diminished orincreased according to the needs of particular examination by usingamplifiers provided with variable mu tubes, or by the use of kinescopein which gamma can be controlled. The signal to noise ratio of thissystem and therefore the definition of the reproduced image may beimproved by using in amplifiers discriminating circuits which rejectsignals below the predetermined amplitude and eliminate therefore mostof the noise signals. The coaxial cable 43 within the examined part maybe encased in the above described means asf/asse l 26 or 26a forinserting the intrascope or may be attached to them.

The voltages for the operation of the tubes 16a and 16b are suppliedthrough the flexible elastical wires 8a from the source of theelectrical power 9 outside of the examined part. In the same way thehorizontal and vertical synchronizing circuits, focusing fields anddeilecting circuits are supplied with electrical energy from the outsidesource of power 9. The synchronizing and deliecting circuits andfocusing fields are not described in detail as they are well known inthe art and it is believed they would only complicate the drawings. Insome cases the coaxial cable 43 may be outside of said inserting means26 or 26a.

The housing 14 containing the television camera can be rotated in itsposition in the intrascope, so that the optical system 15 can be made toface the window 18 or 18a and to see thereby various areas of thecircumference of the examined part. The rotation of the camera can beaccomplished by means of a pusher 15a which fits into extensions 10b ofthe box 14. The rotation of the camera may be preferable in some casesto the rotation of the whole intrascope which allows to accomplish thesame purpose.

The main rigid portion of the exible intrascope is the television camera16. Therefore the shorter the television camera is, the easier it willbe for the intrascope to pass through sharply angulated or curvedpassages. One of the advantages of the novel pick-up tube 16 is that itmakes it possible to break up the smallest pickup tube into twocomponent parts such as tubes 16a and 16b and introduce each of saidtubes int-o the examined part separately, reducing thereby considerablythe rigid portion of the intrascope which is due to the televisioncamera, as shown in Fig. la.

To accomplish these objectives the flexible intrascope 1a shown in Fig.la, is introduced first into the examined part while containing only thebox 5 housing the light source 7. Inside of the intrascope 1a,proximally to the box 5 there is a ring-like partition which serves as astop 27 for the pick-up tube 16b which is to be introduced later. It isobvious that the shape of this stop may vary. The rest of the intrascope1a is empty. The intrascope 1a is introduced first into the examinedpart. As the only rigid part of the intrascope is now the box 5 which isvery small, this intrascope can easily pass even through very narrow andcurved passages. After the intrascope 1a has been introduced into theexamined part for a desired distance which can be read easily on themarkings provided on the outside wall of the intrascope, the next stepbeings. Now the housing box 14b in which the vacuum pick-up tube 16b ismounted is introduced into the intrascope. The housing box 14b is pushedinto the intrascope until it reaches the stop 27, which can be alsoascertained by the X-ray control. The box 14b may be held against thestop 27 by spring extensions 27a, as shown in Fig. 1, on said stop 27.The housing box 14b may be pushed into its position by a liexibleelastic guide 15a which is tted into the proximal end of the housing box14b. For this purpose the housing box 14b is provided with a ring-likeextension 10a at its base which has spring-like properties. The head ofthe exible pusher 15a fits into this extension and is kept in positionby it. The flexible pusher 15a may also be provided with electricalcoils 6a at its distal end which is adjacent to the element to beintroduced into the intrascope. The coils 6a are connected t-o thesource of electrical power situated outside of the examined part. Inthis way, the head of the pusher may be given electromagnetic propertiesby closing the circuit, energizing said coils 6a. The pusher 15a will beheld therefore in the elements to be introduced into the intrascope,such as boxes 14a, 14b or the optical system 15, not only by themechanical pressure of the extensions a or 10b, but by magneticattraction as well. When the pusher 15a is to be withdrawn, the currentsupplying the coils 6a is shut off. To facilitate the guiding of the box14b into the intrascope, a set of threads 86, as shown in Fig. 1b, maybe used which are at one end attached to the stop 27, and which arethreaded through the perforations in the extensions 87 of the housingbox 1411. After the box 14b has been introduced into its proper positionin the intrascope, the pusher 15a is removed. Another set of threads 89is attached to the extensions 88 in the housing unit 14b and serves topull out said box 14b to the exterior of the examined part when theexamination is finished.

The housing box may be omitted in some cases and the tube 16b may beintroduced into the intrascope without any housing and will be held inposition by the same means as described above for holding the box 14b.

After the box 14b with the tube 16b has been introduced, the box 14ahousing the tube 16a is introduced now into the intrascope in a similarmanner as was described above. Both boxes 14b and 14a have openings attheir proximal and distal ends respectively, which makes it possible tobring the uorescent screen 31 of the tube 16a in close apposition to thephotoemissive electrode 33 in the tube 16b. The boxes 14a and 14b areprovided with mechanical means for securing a good contact of theproximal end of the tube 16b with the distal end of the tube 16a. Oneway of providing such a contact is to make the compartment 14a litinside of the spring-like ange 27a at the proximal end of thecompartment 14b. The housing box 14a contains vacuum tube 16a which hasbeen described above. The housing box 14a is provided with spring-likeextensions 10b which serve to accommodate the head of the pushing guide15a.

' The housing box 14a is pushed into the intrascope until it reaches theposition of the st-op 27b. This can be also checked by the X-raycontrol. The stop 27b is so situated that when the housing box 14areaches it the tubes 16b and 16a will be in apposition to each other. Insome cases flexible coils which can be converted into magnets by passingthrough them an alternating current from an outside source of electricalpower may be provided on the stops 27 and 27b or at extensions 10a or10b of the intrascope to help the positioning of boxes 14a and 14b. Inthis way the rigid portion of the intrascope which has to pass through anarrow passageV or acute curvature is now only a fraction of the rigidpart of intrascopes which use even the smallest pick-up tube ofconventional type. This represents an important improvement as it makesit possible to introduce Athe intrascope into parts which were notaccessible previously to examination.

It should be understood that all my intrascopes can serve for 'producingand transmitting color images as Well. The color system may be ofmechanical type such as using a color wheel, or may be of electronictype, such -as using an optical system to split the light image into itscomponent colors and to project them on television pick-up system.

In some applications even my novel intrascopic device cannot beintroduced through the narrow or angulated passages. For such cases Idesigned a novel apparatus which will overcome even to 360 bends inpassages. Fig. 2 shows this embodiment of my invention. The intrascope50 is provided with a novel image conductor 51. The image conductor 51consists of multiple fibers of material having a high refractive indexsuch as quartz, rutile or special plastics. In many applications theimage conductor must be flexible and easily malleable.

In such cases acrylic plastics such as Lucite or poly-- ducted by them.Such materials cannot conduct a whole nuage as such but they can conductwell a light signal, 1t means an image point. The size of the imagepoint I found is determined by the diameter of a single conducting ber52. In my image conductor I assembled a bundle of such bers which form amosaic-like end-faces and which therefore can conduct plurality of imagepoints. All these image points will reproduce at the other endface ofthe image conductor the original image provided that the imageconducting bers remain in their original spatial relationship. Each ber52 should have, as was explained above, a diameter corresponding to thesize of one image point. The diameter of 0.1 millimeter is well suitablefor the purposes of my invention. In order to conduct an image of anarea, e. g., of one square centimeter we must have many fibers 52, thenumber of bers being dependent on the resolution of reproduced imagethat we desire. If the resolution of the conducted image should be 4lines per millimeter, and if the image is of one square centimeter insize, we will need 40 fibers of 0.25 millimeter in diameter. As in manyexaminations it is not practical to be limited to the eld of l cm?, Ipreferably use a few hundred of such bers combined in one imageconductor, which will allow to transmit an image of a large area.

The light conducting fibers should be polished on their external surfacevery exactly. They may be also preferably coated with a very thin lightopaque layer which should have a lower index of refraction than thelight conducting ber itself. Such coating may have a thickness of only afew microns. I found a great improvement of flexibility of the lightconductor 51 can be obtained by having the light conducting bers 52glued together only at their end-faces 51a and 51b. This is a veryimportant feature of my device because the main requirement from thelight conductor 51 is its exibility and malleability. If the bers 52 areglued together along their entire length the flexibility andmalleability is so much reduced that it may be not possible to use it inmany examinations in which the walls or passages are fragile and may bedamaged by a rigid instrument. I found unexpectedly that having theconducting bers 52 free along their path between the end-faces will notcause any deterioration of the conducted image. I found that in spite ofthe fact that bers between their end surfaces were freely movable therewas no blurring of the conducted image. It must be understood, however,that the bers 52 at both end-faces of the conductor 51 must rigidlymaintain their spatial relationship. Another important feature of thisconstruction is that the diameter of the light conductor 51 can be nowincreased because no space consuming binder or glue is present betweenthe bers 52 except at their end-faces. Instead of using the binder atthe end-faces of fibers 52, they may also be held together at theirend-faces by a ne mesh screen. Each ber is threaded through one openingof said mesh screen and is being held by said screen in constantposition.

It may be added that smaller losses of light may be obtained if the bers52 are hollow inside instead of being solid. An improvement in contrastof conducted images can be obtained by coating light conducting bers 52with an opaque material which eliminates the leakage of light from oneber to the adjacent one.

The number of bers that can be used in many examinations will be limitedby the diameter of the passages through which my intrascope has to pass.As in many situations the channel may beonly 1-2 cm. wide it will beimpossible to use a great number of bers. I succeeded to overcome thislimitation, by using in combination the light conductor 51 with ademagnifying optical system 53. By the use of the demagnifying opticalsystem I can reduce the examined eld to the diameter of magnify theimage five times, I can examine the eld having 25 cm.2 with the imageconductor having the diameter of only 1 cm?. This combination representsa very important feature of my invention as it is not always practicalor feasible to limit the examined eld only to the diameter of the imageconductor. Another important feature of my optical system 53 is that itallows to project the image on the end-face 51a of the light imageconductor from which it can be transmitted to the other end of theconductor. If the image were projected on the side of the conductor 51instead of on its end-face, it would not be conducted at all. This isaccomplished by means of the gable prism 53a.

The light image conductor 51 may be introduced into examined partsimultaneously with the intrascope. In some cases it is preferable tointroduce my intrascope first and then insert the image conductor 51 or70 into intrascope. In some cases the gable prism 53a or the wholeoptical system 53 may be attached to the endface 51a of the imageconductor to make one unit. The novel intrascope 50 may have the sameconstruction of other parts as was explained above and illustrated inFigs. l, 1a"and 1b.

Fig. 2 shows the novel intrascope which comprises my novel imageconductive system. The end-face 51a serves to receive the image. As wasexplained above the image is projected on the end-face 51a by theoptical system 53 and is at the same time demagnied to reduce the sizeof the image to the size of the cross-section of the image conductor 51.The image is conducted by the multiple exible bers 52 which form theimage conductor to the end-face SIb. The image emerging from theend-face 51b is projected by the optical system 54 on the televisionpick-up tube 55. If necessary the optical system 54 may be of magnifyingtype to enlarge previously demagnified image of the examined part. Thetelevision pick-up tube 55 may be of the novel type described andillustrated in Figs. 1, la and 1b. It should be understood, however,that all types of television pickup tubes can be used in my intrascopein combination with image conductor 51. The television pick-up tube maybe of conventional vacuum tube type. The television pick-up tube may beof photo-emissive type, photoconductive type, or photovoltaic type. Thetelevision pick-up tube may be of velocity modulation type. Thetelevision pick-up tube may use fast or slow scanning electron beam. Thenovelty of the combination of my image conductor with my televisionpick-up system resides in the ability of the intrascope provided withthis combination to penetrate into locations which were inaccessible tomy television pick-up system and to transmit said image from saidinaccessible locations to the television pick-up tube. The televisionpick-up tube can then transmit the image to the outside of the examinedpart by means of coaxial cables and it can do it regardless of thedistance between the television tube and the outside. The imageconductor on the other hand is limited in its ability to conduct animage to the length of about 15 cm. because of prohibitive losses oflight. Therefore, the combination of the image conductor with atelevision tube represents an important improvement in the art of theexamining recesses inaccessible to direct visualization or toconventional optical systems. It should be understood that my systemwill be also capable of producing color images. For this purpose therevolving color wheel 56a may be provided in front of the televisioncamera 55. Instead of the color wheel an optical system may be providedwhich splits the image into two or three color images and projects saidimages on different parts of the photocathode. It should be understoodtherefore that my invention may use all types of television pickup tubeswhich can produce color images.

I found that the image conductor 51 causes severe the image conductor51. If the optical system will de- Il losses of light. This loss oflight iS dependent 0f the `11 length of the image conductor, on thenumber of bends and angle of said bends to which image conductor issubject in its passage to the examined part. I found that losses oflight become prohibitive when the length of the conductor is about l cm.In some examinations the television pick-up tube cannot be activatedwith the amount of light available after the passage through the imageconductor, because the optical system 54 disposed between the imageconductor and the television pick-up tube causes an additional loss of95% of useful light. In such cases I am using the embodiment of myinvention shown in Fig. 2a or 2b. In this modification of my inventionthe image conductor extends through the wall 55a of the pick-up tube 55inside of the tube. The photoelectric photocathode 56 is now depositedon the 'end-face Slb of the image conductor. The photocathode `56 may beof the photoemissive type as shown in Fig.

2a or photoconductive type as shown in Fig. 2b. In this construction theloss of light caused by the optical system 54 is completely eliminatedwhich represents a thirty-fold increase in light available for thetelevision pick-up tube and which makes the television pick-up tube nowresponsive to the image. The image conductor is cemented to the end wall55a of the tube 55 by the vacuum type seal. In some cases it may bepreferable to provide a support for the light image conductor near theface 55a of the television tube to reduce the pull of the imageconductor 51 against the wall of the pick-up tube.

Another modification of my intrascope is shown in Fig. 3a. In thisembodiment of invention the image conductor 51 has its end-face 51aadjacent to the distal end of the intrascope. The window 91 can beopened by mechanical means which are well known in the art and theend-face 51a of the image conductor 51 may be brought slightly forward.This will result in apposition of the image conductor with the examinedpart. In this embodiment of the invention the light source forillumination of the examined part may be provided at the proximal end51b of the image conductor. The light source 7a projects the light ontomirror which has the property for partly reflecting and partlytransmitting the light. Such mirrors are well known in the art and it isbelieved therefore that their detailed description is not necessary. Thelight reflected by the mirror 58 is conducted by the image conductor 51to the examined part and forms an image thereof. This light is reflectednext by the examined part and returns again through the image conductor51 to the outside. As the mirror 58 is half-reflecting andhalf-tansparent the image of the examined part can pass through themirror 58 and be focused by the optical system on the photocathode ofthe television pick-up tube.

Another preferred embodiment of my invention is shown in Fig. 3. Theintrascope in this modification consists of a rigid part 2, flexiblepart 2a and semi-ilexible tip 3. The mechanical construction of theseparts is the same as described above and does not have to be repeated.The internal image producing and transmitting structures of the flexiblepart 2a are completely different. In particular the illuminating system7 is rcplaced in this modification by the flying spot kinescope. Theminiature fiying spot kinescope 16a or 76 was shown in Fig. l and is avacuum tube provided with an electron gun 28 producing a fine beam ofelectrons 29, with circuits 30a and 30h for dellecting said electronbeam in two vmutually perpendicular directions and also having a screen31 coated with a fluorescent material. The electron gun consists of anelectron emission source and an electron-optical system to focus theelectrons into a fine beam. The fluorescent screen of the kincscope mustbe of a phosphor of a very short persistence in order to obtain a goodresolution of image. ZnO phosphor has decay time of one microsecond andis suitable therefore for this purpose. Still better results will beobtained by applying ZnS phosphor and utilizing only the ultravioletcomponent of its fluorescent emission, which has'4 the decay time of1,60 microsecond. The electron beam of the kinescope has to scan thefluorescent screen in a predetermined pattern. This scanning motion ofthe electron beam is obtained by the electrostatic or magnetic fields30a or 30b, which produce deflection of said beam. This scanningelectron beam Z8 produces a scanning light spot which illuminates theexamined part through window 12 and produces successive image points ofSad examined part. Successive image points are admitted through window18 into intrascope and are projected by the optical system 15 on the endface of thev image conductor 77. The image conductor 77 in thismodification of my invention consists of a single rod of material, whichis flexible and has a high index of refraction, such as Lucite, acrylicplastics, poly-styrenes or other materials. As was explained above, suchmaterials cannot conduct an image. They can conduct a light signal only.In my novel device, the image is produced by a rapid succession ofsingle image points. Each image point can be conducted by the conductor77, because it represents only one signal. Each conducted image point,after it emerges from the conductor 77, is projected on a single orplural photo-tubes or photocells and is converted thereby into anelectrical signal. If black and white image is suflicient, only onephoto-tube 78 has to be used. The photo-tube converts, as was explainedabove, each light image point into an electrical signal. The successiveelectrical signals are conducted by flexible coaxial cables 81 to theoutside of the intrascope and of the examined part. These transmittedelectrical signals are next fed into appropriate receivers, such askinescopes, facsimile receivers or skiatrons, known also as a dark tracetube and are reconverted into a visible image for inspection or forphotographic recording. In case a color image of the examined part isnecessary, we may use two or three phototubes or photocells. Thephototube 78a will serve to receive red image points; phototube 78b willserve to receive green image points, and phototube 78e` will receiveblue image points. vA white light image point may be split into itscomponent colors by the use of suitable optical system. Dichroic mirrors80 are useful for this purpose. It should be understood, however, thatthere are many optical means that can be used instead of said dichroicmirrors. In some cases, it is preferable to use, instead of dichroicmirrors, the rotating color disc 56a. The importance of thisconstruction lies in the fact that I may use now one photo-tube or onephoto-cell instead of three phototubes, which will markedly reduce thesize of the intrascope. In this modification, the speed of the flyingspot produced by the kinescope 76 has to be increased so that the wholeexamined area may be illuminated during the time in which one of threecolor filters of the disc 56 is in front of the single phototube 78. Therotating color wheel 56 may be set in motion by a miniature motor, suchas used in electrical wrist watches, and which may be disposed withinthe intrascope. In such a case, the color wheel may be mounted on theshaft of said motor. In some cases it is preferable to have the motordisposed outside of the examined part. In such event, the motor may beconnected with the rotating disc 56 by means of flexible cables or thepower may be transmitted from the motor to the disc by pneumatic meansor hydraulic means. The pressure exerted by the motor on a column of airor fluid is propagated 'by said pneumatic or hydraulic means to the discand will cause its rotation.

The reproduction of color images may be improved by having in front ofeach phototube or photocell 78a, 78b and 78e, suitable filters 79a, 79band 79e, which transmit only red, green and blue light respectively.

It should be understood that all types of phototubes .or photocells maybe used for purposes of my invention.

In particular I may use phototubes of photoemissive type,

of photo-conductive type or photovoltaic type. The photocells havingsilicon, germanium or bismuth in combination with antimony or aluminumwith antimony are most suitable because such photocells show high frequency response, which is necessary for the operation of my device. Alsomodilied photo-transistors, which have a large photo-sensitive surfacein contradistinction to the conventional ones, in which thephoto-sensitive area is very small, may be used in my invention.

It may be added that when dealing with short dis tances, which do notcause a prohibitive loss of light, the light conductor77 may extend tothe outside of the examined part and the image then may be examineddirectly without the need of conversion of light image points intoelectrical signals, as was explained above and illustrated in Fig. 3. Insuch cases the image points, which appear successively at the end face77 b of the light conductor 77, may be projected by an optical lens andmay be seen by the examiner directly because, due to the persistence ofvision, the successive image points conducted by the conductor 77 willreproduce a total image in the retina of the examiner.

In some cases the light conductor 77 does not have vto extend to theoutside of the examined part, but it may be used in combination with anoptical system, which will deliver the light image from the end-face 77bof the conductor to the outside of the examined part. This arrangementis feasible only in locations in which the course of the examinedpassages between the end-face 77b of the conductor and the outside iswell known in advance, so that a suitable optical system can beprovided.

In some applications where the distance between the examined part andthe outside is small, also the image conductor which consists ofplurality of fibers conducting light may be used without a televisionsystem. This embodiment of my invention is shown in Fig. 4. The lightimage produced by the light source 79 is conducted 'by the imageconductor 70 to the outside where it can be examined visually, recordedor photographed. In some cases the light conductor 70 does not have toextend to the outside of the examined part because the course of theexamined part becomes straight. In this event it is preferable tocombine the light image conductor with an additional optical systemwhich will project the image from the intrascope to the outside of theexamined part.

Another embodiment of my invention is shown in Fig. 5 in which the lightsource is disposed outside of the examined part and is projected ontothe end-face of the image conductor 70 by the half-refiecting and halftransparent mirror 58, as was explained above.

The light image of the examined part which is trans# mitted by the imageconductor 70 to the outside in some cases may be too weak for visualinspection and may require dark adaptation of the eyes. In such casesthe image will be also too weak for photographing. For such examinationsI made a modification of my inven tion which is shown in Fig. 6. In thisembodiment of my invention the image conductor 70 is inserted intovacuum tube 60 through its wall 60a. The photocathode 61 of the vacuumtube which may be of photoemissive type or photoconductive type isdeposited on the end-face SIb of the image conductor. The light emergingfrom the end-face Slb can now excite the photocathode 61 as the opticalsystem is eliminated, which as was explained is causing a prohibitiveloss of light. The electrons emitted from the photocathode 61 are imagedby magnetic or electrostatic lenses 64 and are focused on thefluorescent screen 62 disposed at the other end of the tube andprotected by the light-reflecting layer 62a such as of aluminum. Theelectron image may be also intensified by accelerating iields 64.Furthermore it may be intensified by electron-optical diminution whichresults in an increase in intensity proportional to the square power oflinear demagnilication.

This may be accomplished by means of electromagnet 63 or electrostaticlenses 64. The electrostatic lenses may be in the form of series ofcylinders or rings of progressively smaller diameter. They are disposedinside of the tube and are connected to an outside source of potential.The magnetic or electromagnetic lenses may be in the form of coilssurrounding the tube from outside. Such coils may be tapered or may bein the form of a short coil extending from some point between thephotocathode 61 and the fluorescent screen 62, up to said uorescentscreen 62. The intensified image which appears on the uorescent screencan be inspected visually by the observer directly or may be firstmagnied by an optical eye-piece 64a. The optical magnification of theelectron-optically diminished image does not result in its loss ofbrightness as long as said magnification does not exceed certain limits.In this way the the intensification of the image obtained by means ofelectron-optical diminution is not lost although the image is magnifiedagain optically. Therefore the image of the examined part which was tooweak for examination can now be presented with necessary brightness.

The use of the image tube 60 may also be necessary when using as animage forming radiation an invisible radiation such as ultra-violet orinfra-red. In cases of which the preservation of light is not criticalit may be possible to project-the image emerging from end-face 51b ofthe image conductor 70 on the photocathode 61 of the image tube byoptical means. In cases in which the delinition reproduced image is notimportant, the end-face 51b of the image conductor 71 may be attached tothe end-face of the image tube to be in tight apposition to the externalsurface of the image tube 60. The thickness of the wall of the imagetube 60 which separates the end-face Slb of the image conductor from thephotocathode 61 which will cause however a marked blurring of the image.The image tube may be also advantageously used within the intrascope inorder to intensify the weak image emerging from the end-face of theimage conductor before it is being projected on the television pickuptube. In this embodiment the image tube has to be of miniature size.This can be accomplished by eliminating focusing electrodes and bringingthe photocathode 61 very close to the tiuorescent image reproducingscreen 62 to prevent blurring of electron image.

In some cases it is preferably to use as the light 7a or forillumination of the examined part a polarized light. The image conductedby the image conductor to the observer is not polarized any more due tomultiple reections. Therefore by providing means which will stop thepolarized light from reaching the observer but will trans mit thenon-polarized light, the contrast of the examined part will be markedlyimproved. This construction is of critical importance, in devices inwhich the light for illumination of the examined part has to bedelivered to the examined part by the same image conductor which servesto return the image to the observer. There are many ways in the art toeliminate the polarized light. Fig. 5 shows one of the means suitablefor the purpose of this invention. The rotating prism 59 serves to stopthe polarized light from the source 65 and it will at the same timetransmit the non-polarized light. The resulting improvement in contrastwill make my device operative in many cases in which without thisimprovement it would not be feasible to examine the received image.

It should be clearly understood that all my intrascopes can serve andproduce and transmit color images as well.

It is also to be understood that in some applications the encasing meansfor the image conductor or for pickup tubes may be omitted.

My invention is not limited to visible light images. All my intrascopesmay be made responsive to invisible images on either side of visiblespectrum by using appropriate photo-sensitive layer in the photocathodeof the television pick-up tube. It is to be understood that all myintrascopes may serve for receiving images formed not only by variouselectromagnetic radiations such as ultra-violet, infra-red, etc., butalso by particles radiation such as neutrons, alpha-particles, protons,electrons or by ions. In such cases the photocathode of the pick-up tubedescribed above may be provided with an atomic particles sensitivephosphor on the side facing said image, or may have a special electronor other atomic particles emissive photocathode.

The embodiment of my invention illustrated in Fig. may be also modifiedby using instead of the image conductor 70, which consists of pluralfibers 52, the conductor 77, which consists of one solid rod of materialconducting light, as was explained above. In order to make thismodification operative, I found that the source of light must be able toproduce a scanning light illumination. Therefore, instead of theelectrical bulb 65 I am using in this embodiment of my invention thellying spot of light produced by a vacuum tube 16a or 76, as wasdescribed above. The remaining parts of my device may be the same asshown in Fig. 5.

I also found that the novel image conductors 51, 70 or 77 may transmitnot only white light but also infrared light and ultra-violet light. Itis to be understood therefore that the term light as used in mydisclosure embraces the visible light as well as the invisible.

Another important discovery was that supersonic waves can be alsoconducted by the conductors 51, 70 or 77. By using as a source of imageforming radiation piezoelectric or magnctostrictive means, we mayproduce supersonic images of the examined part. Piezoelectric means maybe in the form of oscillating crystals of quartz, titanate compounds,Rochelle salts and other similar materials.

As various possible embodiments might be made of the above invention,and as various changes might be made in the embodiment above set forth,it is to be understood that all matter herein set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not n alimiting sense.

I claim: y

1. A device comprising in combination means adapted in size and shapefor introducing said device within the examined body, means forproducing illumination and means for producing an image of the examinedpart, image conducing means operating by internal reection of light anda vacuum tube provided with photoelectric means and with means forproducing electrical signals representative of said image.

2. A device comprising in combination means adapted in size and shapefor introducing said device within the examined body, means forproducing illumination and means for producing an image of the `examinedpart, image conducting means comprising a plurality "of fibers operatingby internal reflection of light, and having the length not exceeding 15centimeters, and a vacuum tube receiving said image and provided withphotoelectric means and with means for converting said received imageinto electrical signals representative of said image.

3. A device as defined in claim 2, in which said vacuum tube withphotoelectric means comprises means for producing a scanning electronbeam.

4. A device comprising in combination means adapted in size and shapefor introducing said device-within the examined body, means forproducing illumination and means for producing an image of the examinedpart, said means for producing said illumination comprising a vacuumtube provided with a fluorescent screen and with a` scanning electronbeam producing scanning illumination of saidfexamined part andformingthereby successive image points of said part, light conductingmeans operating by 'the internalfreection of light and transporting saidsuccessive image points, and a vacuum tube having photoelectric meansfor receiving said successive image points and converting said imagepoints into electrical signals representative of said image points.

5. A device as defined in claim 4, which comprises in addition means forproducing color point images of said examined body. f

References Cited in the file of this patent UNITED STATES PATENTS731,496 Poirier et al June 23, 1903 944,830 Sussmann Dec. 28, 19091,751,584 Hansell Mar. 25, 1930 1,848,814 Allen Mar. 8, 1932 2,341,745Silverman et al Feb. 15, 1944 2,354,591 Goldsmith July 25, 19442,433,971 Adams Jan. 6, 1948 2,541,976 Bogart Feb. 20, 1951 2,555,424Sheldon June 5, 1951 2,632,801 Donaldson Mar. 24, 1953 2,649,500Fedorchak Aug. 18, 1953 2,755,390 Teichmann July 17, 1956 FOREIGNPATENTS 604,198 Great Britain June 30, 1948

